And the article posted by D21 failed miserably in knowing that PS3 have always been ahead of X360 launch aligned and except for one year it also have always outsold it on calendar year. The sole reason for X360 being ahead most of the gen (and never significantly) was launching first.
While this is true, the PS3 was coming off of a generation where the PlayStation sold five times as many consoles as Xbox. Early last gen, Xbox was a "non competitor" that many felt would suffer the same fate as the Dreamcast. There's a quote that I read in a magazine that went something like:
Sony: "We've been in this position before. PS1 first, N64 after. Dreamcast first, PS2 after. It doesn't matter what the Xbox 360 sells. We'll overtake that quickly and it'll be business as usual."
Somewhere along the way, the Xbox 360 turned into a real competitor and Sony really did have to start taking them seriously. I don't think the 360 even reached their goal of 10 million in the first year. Sony slowly chipped away at the lead but it took pretty much the entire gen and a lot of money loss to earn a "victory".